What a joint module test covers
A joint module integrates motor, reducer, encoder and drive, so the test list covers rated and peak torque output, efficiency and temperature rise, transmission error and backlash, torsional stiffness and hysteresis, position and velocity control accuracy, and a burn-in schedule of long reciprocating motion. Torque ripple at low speed is often the parameter that decides whether the robot's gait looks smooth.
Why a burn-in bench pays for itself
Humanoid robots are moving from prototypes to volume, and early-life joint failures decide whether that scale-up works. A multi-station burn-in bench runs dozens of joints on a realistic motion profile for hundreds of hours, screening out assembly defects and infant mortality before shipment while building up a life-distribution data set.
Harmonic reducer specifics
Harmonic drive transmission error is measured in arc-seconds, so the measurement system's resolution and mounting stiffness have to be considerably better than the unit under test. The bench needs high-resolution circular encoders, rigid supports and a thermally stable environment, with measurements repeated over a matrix of loads and speeds before the data is good enough to drive process improvement.